Re: [RFC PATCH 1/2] block: strict rq_affinity

[Shaohua Li]

2011/7/24 Jens Axboe <jaxboe@xxxxxxxxxxxx>:
> On 2011-07-22 22:59, Dan Williams wrote:
>> Some storage controllers benefit from completions always being steered
>> to the strict requester cpu rather than the looser "per-socket" steering
>> that blk_cpu_to_group() attempts by default.
>>
>> echo 2 > /sys/block/<bdev>/queue/rq_affinity
>
> I have applied this one, with a modified patch description.
>
> I like the adaptive solution, but it should be rewritten to not declare
> and expose softirq internals. Essentially have an API from
> kernel/softirq.c that can return whether a given (or perhaps just local)
> softirq handler is busy or not.
Jens,
I posted a similar patch about two years ago(
http://marc.info/?l=linux-kernel&m=126136252929329&w=2).
At that time, you actually did a lot of tests and said the same cpu
approach will cause huge lock contention and bounce. Is that get fixed?

Thanks,
Shaohua
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